Many batteries are rated by a measure of CCA (Cold Cranking Amps) according to an industry standard test procedure. The procedure begins with a fully charged battery. Then, a very large current load is drawn from the battery for a specified time. The test current is based on the presumed CCA rating of the battery. Afterwards, the battery voltage is measured. If the voltage is at (or above) a specified value, the battery is said to have at least the presumed CCA rating.
Battery testers typically determine the condition of batteries, i.e., determine the internal resistance of a battery, by either a load test or a small-signal analysis of the battery. For a classic load test, a very high-current load is applied to the battery for a specified time and battery voltage is measured thereafter. Dougherty U.S. Pat. No. 5,773,977 teaches a tester that uses a bounce-back voltage after a load is removed to determine the condition of the battery. An example of a load tester is the well-known SUN VAT 40 load tester.
Small-signal battery testers determine the condition of a battery by imposing a relatively low current (e.g., on the order of about an amp) AC signal across the terminals of the battery and analyzing the small AC voltage generated as a result of the internal resistance of the battery, e.g., by comparing a value related to battery internal resistance or conductance or impedance or admittance to a threshold value that is a function of the rated CCA value of the battery. Examples of the literally hundreds of patents showing small-signal battery testers include the testers shown in Furuishi U.S. Pat. No. 3,753,094, Bosch DE 29 26 716 B1, Champlin U.S. Pat. Nos. 3,873,911, 3,909,708, 4,912,416, 5,572,136, and 5,585,728, Namaky U.S. Pat. No. 6,384,608 B1, and Cervas U.S. Pat. No. 6,388,488. The testers in Frailing U.S. Pat. No. 4,193,025, Marino U.S. Pat. No. 4,423,378, and Dougherty, et al. U.S. Pat. No. 6,144,185 are examples of testers that use both (i) one or more load tests and (ii) one or more small signal tests to determine battery condition. All of the foregoing patents are incorporated herein by reference. Also incorporated herein by reference is copending U.S. patent application Ser. No. 09/813,104, which was filed on Mar. 19, 2001, and entitled HANDHELD TESTER FOR STARTING/CHARGING SYSTEMS. Various small signal battery testers have been sold by Actron Manufacturing Co., Robert Bosch GmbH, and others.
For virtually every battery tester, the user must enter the CCA rating (or some other rating of the battery) of the battery into the tester, e.g., with a knob or dial or via a processor-driven user interface. This requires the user to identify the Cold Cranking Amps (“CCA”) rating for the battery, and enter that number into the tester. Determining the CCA rating for the battery can be difficult because the battery's information plate is often covered with dirt and grime to the extent that the CCA rating is illegible. In this situation, to determine the CCA rating, the user must clean off the battery nameplate, while being careful to avoid being shocked or burned. Sometimes it is very difficult to access the side of the battery that indicates the battery rating. Also, it is not uncommon for the battery name plate to be entirely missing. Moreover, even if the battery passes the battery test, the user often has no idea if that battery is the proper size for the vehicle in question and must, therefore, consult a secondary reference, such as the owners manual, to determine whether the battery CCA rating is equal to or higher than the required CCA rating for the particular vehicle.